The field of the invention relates generally to electrical machines, and more particularly, to air cooling systems for electric machines.
One of many applications for an electric motor is to operate a pump or a blower. The electric motor may be configured to rotate an impeller within a pump or blower, which displaces a fluid, causing a fluid flow. Many gas burning appliances include an electric motor, for example, water heaters, boilers, pool heaters, space heaters, furnaces, and radiant heaters. In some examples, the electric motor powers a blower that moves air or a fuel/air mixture through the appliance. In other examples, the electric motor powers a blower that distributes air output from the appliance.
A common motor used in such systems is an alternating current (AC) induction motor. Typically, the AC induction motor is a radial flux motor, where the flux extends radially from the axis of rotation. Another type of motor that may be used in the application described above is an electronically commutated motor (ECM). ECMs may include, but are not limited to, brushless direct current (BLDC) motors, permanent magnet alternating current (PMAC) motors, and variable reluctance motors. Typically, these motors provide higher electrical efficiency than an AC induction motor. Some ECMs have an axial flux configuration in which the flux in the air gap extends in a direction parallel to the axis of rotation of the rotor.
One problem associated with electric machines is that it is necessary to cool them because they generate heat, which reduces their efficiency and useful life. Motor components such as the stator and electronics boards generate high temperatures and are subjected to substantial thermal stresses. Accordingly, efficient motor cooling systems are necessary to prevent overheating of the motor components and to improve the overall electrical and mechanical performance and lifetime of the motor. Some known electrical machines may be air cooled by blowing air through or over them. However, some known air cooling designs are inefficient.